Gravitational potential energy. Please help!!! 1. The problem statement, all variables and given/known data A projectile is launched from Earth's surface at a speed of 10 km/s. Find the maximum height it reaches. 2. Relevant equations change in U = -change in K U = -GM/r 3. The attempt at a solution GMm/r = 1/2mv^2 ((6.67x10^-11)(5.98x10^24))/r = 1/2 (10^4m/s)^2 r = 1.5x10^6 m the answer is supposed to be 2.5x10^7 m ???